class Solution {
    public int uniquePaths(int m, int n) {
        int[][] db=new int[m][n];
        for (int i=0;i<m;i++){
            for (int j =0;j<n;j++){
                if (i==0||j==0){
                    db[i][j] = 1;
                }else {
                    db[i][j] = db[i-1][j] + db[i][j-1];
                }
            }
        }
        return db[m-1][n-1];
    }
}